The frequency of this circuit, for the indicated components, is 1 kHz. Other operational amplifiers can be used, and the power supply must be symmetrical.
This transistor source was found in a 1990 documentation. 2N3055 transistors must be equipped with...
This tube circuit is from an 80's documentation. The filter is of the selective type and the...
This general-purpose two-transistor circuit was found in the November 1993 issue of Electronics Now. The...